Mark Oaten resigns from his post after liaisons with a gay prostitute. Charles Kennedy is forced out because of a drink problem. Several rungs down the political ladder, George Galloway pretends to be a cat in the Big Brother house. The most striking midwinter images are dark, comic and, in some cases, sad.

They are much more than that. I recall the agonies of some voters over which party to support at the last election. A few switched to Mr Galloway's Respect Party. He responds by performing in a leotard. It is the sort of eccentric misjudgement only made by leaders of small parties unconstrained by the prospect of power.

But in very different ways, those voters who turned to the Liberal Democrats have cause for grievance too. What should the anti-war Labour supporters do? It was one of the election's big themes. Some stayed with Labour in the end. Others made the move. These were serious people making what they took to be a big decision, placing faith in the smaller third party. The faith has not been repaid.

The cover-up of Mr Kennedy's drink problem remains more disturbing than the problem itself. What an extraordinary act of self-disciplined deception it was. The MPs knew, but none of them broke cover. Many factors explain their actions including electoral expediency and decent loyalty, but on one level they must have concluded that neither they nor their leader would be greatly tested in the years to come, at least by the burdens of power. Either that or they have exaggerated the scale of Mr Kennedy's drink problem, which is possible given that they were not candid before.

Mr Kennedy's own behaviour also demands a little more scrutiny. Why did he cling on so determinedly to his post when he did not seem to enjoy it greatly even when he was doing well? I do not believe that sheer bloody- minded vanity is an adequate explanation. I suspect Mr Kennedy acted stubbornly partly with his party in mind. He had no great faith in his own MPs to sort matters out if he went. His project was to keep a restless party united under his pragmatic leadership and hand over to a younger MP after the next election.

For a political party, these are all symptoms of extreme fragility: a leader with a drink problem and MPs covering up for the problem even though the leader did not have a great deal of confidence in some of them. Presumably it was in such a context that Mark Oaten assumed he could stand in a leadership contest brought about partly by a cover-up even though he had his own story to hide. Mr Oaten must have worked on the assumption that long-term national anonymity and media indifference was guaranteed even if he became leader of the Liberal Democrats.

A Liberal leadership contest is tainted once more by scandal. In the shadow of the Jeremy Thorpe affair in the late 1970s, the main issue in the leadership contest was over whether one of the candidates had opted for a hair transplant. Now the bleak political context means that candidates take part in television reports on the possible skeletons in their cupboards.

But perhaps they would welcome a debate on potentially more divisive ideological terrain. The BBC website is currently showing a fascinating interview with Shirley Williams conducted 25 years ago after the Limehouse Declaration, the formal beginning of the SDP and the split from Labour. In the interview from 1981, she was asked about her view of the Liberal Party and its leader at the time, David Steel. Ms Williams expressed her admiration for Mr Steel but observed: "There are many Liberals to the right of David Steel, and I would have problems making common cause with them."

Although Ms Williams became a keen advocate for a merger with the Liberals, nothing much has changed. She is a modern social democrat, one of the most articulate on the national stage. Some in her party are right-wing economic liberals. Still, there is limited common cause.

Were Shirley Williams and her colleagues wise to leave Labour in 1981 in order to form their own party? Another senior defector David Owen tells me that he had no choice. It would have been impossible for him to stand on Labour's manifesto in the 1983 election. He also takes the fashionable view that the SDP helped to create New Labour. But I sense he agonises retrospectively. He tells me he contemplated fleetingly rejoining Labour in the mid 1990s, a sign perhaps of a yearning for a party with a capacity to win power.

It is at least arguable that four election defeats and Thatcherism gave birth to New Labour. If Williams, Owen and co had stayed put they would have played more directly influential roles in the 1997 Labour government, bringing experience and possibly a much- needed radical edge.

Forming smaller parties and voting for them can be deceptively attractive, but only for a short time. George Galloway could not find enough breathing space to flourish in Labour, still a broad church that contained many vocal opponents of the war against Iraq. Now his small party reels as it adapts to his new image, a team player but only in the Big Brother house. I doubt if it will survive. Parties dependent on the personality of a maverick leader never do.

A multi-party system is not always a sign of a healthy democracy and can sometimes be quite the opposite. In Russia, there are plenty of political parties but none of them are securely based. They come and go on the whim of a billionaire's vanity or the ego of a single individual. In British national politics, smaller parties flourish when the main two large coalitions are in poor shape. Yet even then, under the current voting system they cannot wield much influence. The distance from power seems to breed a casual recklessness in some of the representatives at Westminster.

At the moment, Labour is split over Mr Blair's so-called "reform agenda". David Cameron is proving to be an astute leader of the Conservatives but he will also be forced to take note of his party's worries when it fears he is moving too far. At least the two bigger parties are conducting serious debates about the future direction of the country and retain a hunger for power while the Liberal Democrats adjust to the consequences of drink and sex. Not surprisingly, Lib Dem activists are alarmed and fear the local elections this May.

The Liberal Democrats are in a different league to Respect and other fringe parties that come and go. But in the early 1980s when the SDP soared briefly, there was much talk of multi- party politics. The same theme surfaced in the mid 1990s as Mr Blair and Paddy Ashdown formed a close relationship. Nothing happened. Without a hung parliament, the key battles will be fought always between and within the two bigger parties. That was the case then, and in the current circumstances is even more the case now.

s.richards@independent.co.uk